Silicone resins are useful in a variety of applications by virtue of their unique combination of properties, including high thermal stability, good moisture resistance, high oxidation resistance, low dielectric constant, and high transparency. For example, silicone resins are widely used as protective or dielectric coatings in the automotive, electronic, construction, appliance, and aerospace industries.
Although silicone-resin coatings can be used to protect, insulate, or bond a variety of substrates, free-standing silicone-resin films can have limited utility, owing to low tear strength, high brittleness, low glass transition temperature, and high coefficient of thermal expansion. Consequently, there is a need for free standing silicone resin films having improved mechanical and thermal properties.
To obtain transparent reinforced silicone resin films for applications such as fire-rated glass, for example, the refractive index of the silicone resin is kept relatively high. High refractive index can be obtained by introducing a high phenyl content into the silicone resin. But increases of phenyl content disadvantageously can also increase flammability of the silicone resin. As such, there remains a need for silicone resin compositions having suitable refractive indices and also decreased flammability. Decreased flammability in this regard may be quantified through measurements of limiting-oxygen index (LOI) of the silicone resin.